G.M.S., also known as Growling Mad Scientists and GMS, is a Psychedelic trance band composed of Riktam (Shajahan Matkin) and Bansi (Josef Quinteros) which ormed in Amsterdam in the early 1990s. Sebastian Claro and Yakov (Jacob Biton) were also past members of the band.

Groundbreaking psychedelic trance group Growling Mad Scientists -- Riktam (Shajahan Matkin) and Bansi (Josef Quinteros, who is originally from Barcelona)--regularly tour the world and have sold over 200,000 albums on over 150 releases. Their music pushes and blurs sonic boundaries and has inspired both producers and punters alike, making G.M.S. one of the most in-demand live electronic acts in the world.